Balanced impeller structure for wind motors



March 9,- 1948. J. R. ALBERs BALANCED IMPELLER STRUCTURE FOR WIND MOTORS Filed July 19, 1943 4 Sheets-Sheet 1 R g lsA es I6 JOH N R. ALBERS March 9, 1948. J. R. ALBERS l Y 2,437,659

BALANCE@ IMPELLER STRUCTURE FOR WIND MOTORS Filed July 19, 194:5 4 sheets-'sheet 2 Afl/171.0331. lo K H g FIG. 5

JOHN R.A| BERS @www F'G-Z HISATTORNEY March 9, 1948.

J. R. Marinesl BALANCED IMPELLER STRUCTURE FOR WIND MOTGRS Filed' v.my 19, 194s 4 sheets-snml :s

BYMQMSM HIS ATTQRr-JEY Manh 9 1948- J, R. ALBERs 2,437,659

BLANCED IIMPELLER STRUCTURE FOR WIND MOTORS h Filed' July 19, 1943 4 Sheets-Sheef 4 FIG.I5

FIG. I4

l NvENToR JOHN R. ALBERS Bmf A 14 Hls ATTORNEY Patented Mar. 9, 1948 BALANCED IMPELLER STRUCTURE FR WIND MOTORS John R. Albers, Sioux City, Iowa, assignor to Wincharger Corporation, a corporation of Minnesota Application July 19, 1943, Serial No. 495,261

3 Claims.

This invention relates to Wind motors and more particularly to means for balancing the impeller structure of such motors.

Modern Wind motors, particularly in the smaller sizes, operate at very high speeds. At such high speeds, the disturbance in the Wind stream produced by one blade of the Wind motor impeller may not have been carried past the impeller before the next blade turns into the disturbance and this is one of the factors limiting the maximum speed attainable. For this reason, small high speed impellers usually have but two blades and are therefor quite unbalanced gyroscopically, that is, they are subject to rapidly varying forces when while rotating about the impeller axis the direction of the axis is changed. Such change in the direction of the axis of the impeller occurs Whenever the direction of the wind changes, wind motors being commonly provided with tailvanes to cause them to present their plane of rotation perpendicular to the wind.

VIt is common practice to provide a Wind motor With an aerodynamic governing mechanism of some sort. For example, it is known to provide a wind motor with a governing airfoil pivotally mounted on the Windward face of the impeller blade with the airfoil arranged to be moved into governing position by centrifugal force acting against a spring biasing the airfoil into non-governing position. The governing airfoil in governing position deflects air outwardly from the tip of the impeller blade. It has also been proposed to mount a governing device on the leeward side of an impeller blade of a Wind motor. In both of the arrangements described above the addition of the governing mechanism to the impeller blades increases the mass of the blades and hence increases their gyroscopic unbalance.

There has also been used a wind motor in which the governing airfoils are mounted on separate arms at right angles to the impeller blades. This arrangement serves to decrease the gyroscopic unbalance but has the defect that the long arms necessary to mount the governing airfoils in operative position must be of considerable strength and size and consequently cause a substantial drag unless specially designed. Furthermore, such separate arms increase the total cost of the wind motor.

According to the present invention the governing airfoils are mounted on the impeller blades themselves, thus avoiding the use of separate arms, and gyroscopic balance is attained by additional means.

Some of the prior art Wind motors have not depended on the use of governing airfoils for speed regulation, but instead have made use of the socalled side-governing principle according to which the Whole impeller structure is rotated so that the plane of rotation of the impeller blades is no longer perpendicular to the direction of the wind. While such an arrangement does not increase the gyroscopic unbalance of the motor, it increases the importance of gyroscopic balance since every time the side governor operates the direction of the impeller axis is changed. According to another aspect of my invention means are provided for gyroscopically balancing such a side governing motor.

In order to balance a rotating body gyroscopically, it is necessary to cause a homogeneous mass distribution about the axis of rotation. This can be accomplished to a certain degree in the case of a two bladed impeller by adding balancing weights on the ends of a cross arm mounted on the impeller axis at right angles to the line of the impeller blades. While theoretically it may not be necessary that the weights be in the same plane of rotation as the impeller blades, in actual practice because the impeller shaft can bend in between the plane of the weights and the plane of the blades, it is desirable that the weights be placed in the plane of impeller rotation or at least be supported on arms connected to the same part of the impeller shaft as the impeller blades. Otherwise, despite the balanced or homogeneous distribution of the masses when projected onto a plane perpendicular to the axis of rotation, vibrations would be set up whenever the direction of the axis of rotation was shifted due to bending of the impeller shaft as the gyroscopic forces on it varied at points along its length.

For similar reasons it is desirable to mount any governing apparatus on the impeller blades in such a manner as to cause equal distribution of mass on the Windward and leeward sides. This is necessary to avoid creation of gyroscopic moments tending to bend the impeller blades when the axis of rotation ls changed in direction.

It is seen therefore that to achieve practical gyroscopic balance it is necessary to balance the mass distribution of the impeller structure in three dimensions Vand accordingly, it is anobject of this invention to provide an impeller balanced in three dimensions. Y

Another object of this invention is to provide a new and improved governor or spoiler which may be attached to the leeward surface or Windward is provided with means for synchronously deectting the spoilers or governors uniformly.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, both as to its organization :and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a front view of apparatus embodying my invention;

Fig. 2 is a side view of the structure illustrated Figs. 3 and 4 are fragmentary views, partly in section, showing certain partsjofithe structurejillustrated in Figs. 1 and 2;

Fig. 5 is a view taken substantially on line5-5 of Fig. 1 when the member I6 is in the position shown dottedinzFlgl;

Fig.; 6. is afra'gmentary .viemapartly in section, of a portion oftthelapparatus. shown inFig. 1;

Fig.7 is a sectional.view;taken substantially-on lines .'l-'.1. of Figcl;

Fig. Bis .a fragmentaryzviem partly in section, of va modiedstructureembodying my invention;

Fig.. 9 .is .a fragmentary :view .ofanother modied structure embodying :my invention;

Fig. 10'is .falfront'i-.view lof `other apparatus .embodying myinvention;

`Fig..l1 15:2. .fragmentary-view,;.partly in section, showing certainparts'otthe. structure illustrated in Fig. 10;

Fig. 12 isY a .fragmentary view, partly .in section, of .another apparatus `embodying my invention;

Fig. 13 is .arplan tview .cfa further apparatus embodying. myzinvention Fig. 14lis 4a .plan-viewpfpthe apparatus shown in Fig..134 in another.operativeposition;

Fig. .15.is afront viewcof:apositionf'the impeller structureshownin F5913.

The .wind;driven;impeller shownzinFig. 1 comprisesafhub .9..and;apair.of blades :I0 and 'II which areusuallyformedirom a singlepiece of material. The-Windward sides ofthe blade shown in Fig. ,1 :present :beveled sides I2 `and I3 to the wind forxrotation' ofthegcomposite impeller about its center of gravity which; corresponds to the axis of a rotatable shaft-|4 `(Fig. 2).

The impe1ler-.is.fastened ,to the rotatable shaft .I4-bymeanstube-.describedlater. .Shaft I4 may be rigidly;connected toga mechanical Aor electrical device :for transforming `rotational energy Droducedv by rotation -of .the Wind .driven impeller into mechanical 10r :electrical energy. lThat is, shaft I4 maybe .connectedto amechanical vdevice-suchas a-Water pumpLor to an electrical devicesuch as;a generator ,I5 ,arranged to be driven Vby the impeller.

Due to thecharacteristics of -the impeller vsurfaces I2 and I3, theirnpeller shown in Fig. 1 rotates in the directionof the arrow A when wind blows in a directionperpendicular to the plane of the drawngand toward beveled sides I 2 and I3.

Spoilers iorgovernors I6and vI'l mounted re- .spectivelyron the leeward faces 4of each -one of the impelleriblades 1| 0 .and l I for; relative. movement thereonV may-move 1 to assumeztheaposition shown dotted in Fig. 1 under certain .conditions of impeller-rotation. '-.Onezof` the important features of this invention Visthat the;spoilers or governors IB and I-'l areoperated synchronously and cannot operate-'independently Lof one another. :Thei parto operate synchronously are preferably located so that the composite impeller including the spoilers or governors and actuating mechanism therefor produce no unbalance when and as the spoilers or governors are moved. For this reason, among others, the actuating mechanism for spoilers or governors -'I6 vand II is :mounted symmetrically about the'center of gravity. of. the impeller in such a manner that change in moments due to move- .ment of spoiler or governor I 6 with respect to blade .I2,s vexactly compensated by the change due tomovement `of spoiler or governor I'I with respect to blade I I.

rFigs. f3 andaV illustrate the particular manner 'inwhichspoilerll is mounted on its corresponding blade I. vrSpoiler I1 is mounted on blade II in .the same manner. The spoiler or governor 'I is securely xedto shaft I8 which is rotatably mountedin bearing member 20 in impeller IIJ. Bearing member 20 isrigidly held in impeller blade IIlin a'presstftherein. .Arm 22.securely mountedv on shaft I8 is vfreetomove within the angular distance determined-.bystopslA and 26 which may consist .of pegs, press fitted into impeller blade I Il. The endof arm `22 Aremoved from shaft-I8 is rotatably connected to restoring or controlling rod 28, for instance, by inserting a bent end of restoring rod v28 as shown in Fig. 3 through an enlargedhole in arm. 22 and then enlarging the end of therod. Other means may be used for mounting the spoilers .orgovernors I6 and I'I on thev impeller and my invention is not necessarily limited to theparticular means disclosed. Other means maybe used to achieve an important feature of myinvention .wherein the control or restoring rods 28 and .29 .are actuated in response to movement of the spoilers or-,governors I6 and'Il, respectively, and vice-versa.

The spoilersor governor-S16 and-I1 are shaped and spacedrelative to the blades IIJ and I I so as to present a streamlinedsurface when the lmpeller rotates about itsaxisat speeds below the governing. speed. -As shown inFig. 9, each spoiler or governor I6 yandfll is `substantially acrescent shaped blade-and when innen-governing yposition is sodisposedrelative to itscorresponding impeller blade that the mean radius of each spoiler or .governor blade 4corresponds to a radiusR drawn throughthe tips.or.`leading and `trailing edgesof the blade with'the axisofimpellerrotation as a center. .For smoother operation, in :some .instances each. spoiler or governor crescent shaped blade .may berslewed-.a'small angular distance with respectrtofanarc drayi'n.through the center of rotationof .the spoiler `or.governor blade with `the axis .ofimpeller Vvrotation; as a center. For

instance, theJspoiler. or L governor ibladesf-may be skewed as shown'innFigsJlfandA vantllthedegree of skewing, `at speedsbelow governing speed, is determined by 'theposition tof -stop .26 (Fig. 4) with-respect to arm 22.

Control or restoringrods 2Bandv29 servefas rigid links for-transferring movement of 4spoilers or governorsl and Ifl"tothe-common'rotatably mounted equalizing bar '30: and vice versa. Also, as hereinafter explained, the weghtofthe rods 28 .and 429 contributelto the operation of the governing mechanism. The control'or .supporting rods28 and ZIleachhave anendthereof'fastened to opposite endsbf ,the equalizing bar 30. The controlor restoring ro`dsf28` and`29 may be pivotally rnounted-,atthe respectiveendsof the equalizer bar 30 whereby motion of the equalizing bar 28 and 29. The equalizing bar `3II is rotatably mounted at its center of gravity which corresponds to the axis of rotation of the impeller.

Tension springs 36 and 31, having one endV fastened to the impeller and the other end fastened to the equalizing bar 30, maintain a positive pull on the control or restoring rods 28 and 29 so as to maintain positively the spoilers or governors I6 and I1 in a position wherein clockwise movement of the governors I6 and I1 is arrested by the inner stop members corresponding to stop 26 in Fig.` 4. Not only do the tension springs 36 and 31 cause positive biasing forces on control rods 28 and 29, but since they act through the intermediate equalizing bar 3D equal movements are imparted to the spoiler or governing mechanism which is symmetrically mounted about .the center of rotation of the impeller.

As illustrative of the manner in which the elements heretofore described may be mounted about the center of rotation of the impeller, the construction shown in detail in Fig. '1 is now described. The energy transmitting shaft I4 extends through the impeller hub 9 and has a radial hole therethrough for the passage of supporting mem-ber 33 and has an axial hole therethrough for the reception of a shaft 38 which is securely mounted to the energy transmitting shaft I4 by means, for instance, of a modified cotter pin 39. Equalizing bar 30 is rotatably mounted on shaft 38 having head 38A which includes the equalizing bar 3i! between antifriction means, for instance, washers d and EI which are on shaft 33. The impeller hub 9 has a hole therethrough for the passage of supporting member 33 which also passes through shaft I4 and thus prevents movement of impeller hub 9 along the axis of shaft I4. Supporting member 33 has a radial hole therethrough for the passage of shaft 38 and thus member 33 may not move relative to impeller hub 9.

With the apparatus thus far described, rotation of the impeller structure, including the blades II) and II and the spoilers or governors IB and I1, causes two types of force to be present which tend to turn the spoilers or governors I6 and I1 from the full line position illustrated in Fig, 1 to a position approaching the dotted line position. One of these forces is centrifugal in nature, and arises primarily by reason of the tendency of the two rods 28 and 29 and attached members to move radially and outwardly during rotation of the impeller structure. These centrifugal forces may also be caused to arise in part by suitably forming and pivoting the spoilers or governors I6 and I1. For example, as shown in Fig, 12 the pivoting point of the spoilers or governors corresponding to the axis of shaft I8 may be displaced radially outwardly oi the arc correspon-ding to radius R, and as soon as the spoilers or governors I6 and I1 are thrown out of the non-governing position the centrifugal forces on the spoilers or governors will be balanced and will tend to throw them further in the same direction as they were initially moved. Also, as shown in Fig. 11, the pivoting point may be displaced tangentially from the center of the lspoilers or governors IIB and II1 so that they are initially unbalanced in a direction tending to move them to governing position.

The other force tending to move the spoilers or governors arises from Wind pressure, and acts by reason of the fact that the spoilers or governors I6 and I1 (Fig. 1) are skewed a small angular distance from arc R in the non-governing position and hence rest at a small angle of attack to the air as they rotate with the impeller structure. That is, in the non-governing position the leading edges ISA and I1A of the governors I6 and I1 lie further from the rotating center of the impeller structure than do the trailing edges IEB and I1B of those plates. Consequently, air passing the spoilers or governors I6 and I1 presses the leading edge portions I6A and L1A outwardly as measured from the rotating center of the impeller structure.

When the spoilers I6 and I1 are skewed a small angular distance as shown in Fig. 1, there may also be an unbalanced component of centrifugal.

force which tends to cause the spoilers to move to a position approaching the dotted line position, for since some elemental parts of the spoilers or governors are ldisplaced a greater distance from the center of rotation of the impeller structure than other elemental parts, the rst'mentioned elemental parts'have greater centrifugal forces acting thereon to urge them further from the center of impeller rotation, and provided the spoiler or governor is properly shaped, the moment arms on which the first mentioned parts act about the pivotal axis will not be reduced sufficiently to compensate for this unbalance.

Thus, these two forces, namely those arising from centrifugal action of the rods 28 and 29 and movable parts attached thereto and wind forces operating on the spoilers or governors I6 and I1, increase gradually from zero as the impeller structure rotates in the direction of the arrow A (Fig. 1) faster and faster from a point of rest. At a certain speed the total forces tending to turn the spoilers or governors I6 and I1 become equal to the force of springs 36 and 31 tending to maintain the spoilers or governors in their normal ineffective position, and as the centrifugal 1 wind forces increase a slight amount more they overcome slightly the opposing force of springs 36 and 31 and turn the spoilers or governors I6 and I1 out further to a position approaching the dotted position. It is necessary always that the rate of increase of forces tending to `turn governors I 6 and I1 upon displacement of those governors shall be less than the corresponding spring rate of springs 36 and 31.

When the spoilers or governors I6 and I1 are turned from their initial position, they not only do more work on the air than in their initial positi-on, but also spoil the streamlined surfaces of the blades I0 and I I so that the net wind pressure driving the blades I0 and II is decreased. As a result, the rate of increase of speed of rotation of the impeller blades I0 and II upon increase in wind speed above the speed at which the spoilers or governors I5 and I1 turn upon increasing wind velocity is much less than at lower speed rotation.

It is to be noted that the spoiler or governor blades are disposed relatively close to the irnpeller blade so that in eiect turbulence near the spoiler plate is directly at the impeller blades. The size of the spoilers or governers I6 and I1 in relation to the tension of the springs 36 and 31 is such as to maintain -the impeller desirably close to a certain maximum speed.

I have thus far shown the spoilers or governors I6 and I1 mounted on the leeward side of the impeller. The governors or spoilers I6 and I1 may be mounted onthe front side or Windward side as shown in Fig. 8. In Figs. 3 and `8, like parts are given identical reference numerals. In the arrangement shown in Fig. 8 the shaft I8 rigidly secured to spoiler plate I6 is rotatably mounted in the bearing 20 which is held in impeller I2 by press fitting orv the like. Shaft I8 may be re- 7. moved ffriom'tneprcpeller 'blad'e #2day removing screw `42 "which fhol'ds tlicshaft f' IIB` 'ltoia' circular ring 43. Circular ring i435 isrcces'sed in -the-irripeller blade so as to retainfs'haft I8 inrbe'aring 20 and maintain a streamlinedsurfac'e off'the ipeller blade I2. lHousingoff1s`treamline`cona guration, serves to encloseffalportionlnf theoperating mechanism and `'offer'sfsmall fair resistance.

With the arrangement sfar' described, lspoilers orgovernors I 6 andl I Ti when deflected from 'their nor-mal `positions cause 'deection of Jthe air firi-Y wardly toward the center'of thef'irripeller'rstructure. lIn the 'modicationsfshown in'Figs.'10 and 11,` spoilers or governors i I |16 arrd I I'I-are mounted so as to cause air to 1" be lde''ectefd outwardly'- as measured fromth'e 'center offrotation of 'theimpeller structure. In the iniodiIcat-ion "shown'in Figs. 'and -11, thefspoi'lersor:governors'I I'B-an'd H1 are lmounted50151 the le`s`ideforia1rfoil sidof the' impeller blades but the"sp'oi1ersor governors I I 6 and I I1 may be mounted onfthe Windward or front side ofthe impeller' blaldelby 4means -of I the constructionsh'own in'Fig. 58. 1InFig's. 1'0 "and 11, parts similar to those already described areigi'ven identical reference numerals'. Except `as stated above, the operation is the :same 'i as vfor Lthe l 'arrangement shown `in Fig, 1.

In each of the-ab-ovefdscribedFarrangenients'it is imperative that theinpellerfstructure beL-:gyroscopically balanced. lIo fthis-end vthe elements comprising thecoinpositelimpeller arefs'yminetiically Vmounted 'about thefa-xis of 'rotation-and in addition cross '-balancinglnan's CFIgs. 1 "and 11-0) are mounted on Vthe impeller. -Theselcros's bal'- ancing means comprise tl'ie'irai'n drop *shaped members 3|l and-32 whicliarem'ounted nfa' supporting rod 33 fastened to hubfQ at1the center of rotation of the-impeller. Theme'mb'e'rs 3l' and v32 (Fig. 6) arepreferablyof rainidropsha'peso as to present astreamlinedTsurfaoe'whenlthe iin-` peller rotates in the direction of the'arrow shown in Fig. 1. The'inernber 132i-i's adjustablyf'm'ounted on rod 33 by meansLf a screwlconneetion Y34 therebetween. In order 'that "a better balance may be obtained, provision maybefincorpbrated inthe structure whereby thefspacing of-mernbrs 3| and 32-relative t'othe impell'er'maybe varied. For instance, Vsp`a'cers3'5 of various thieknessfma'y be disposed between the membersf3 l f:an'df 32 "arid their supporting-rods 33, or the length of? rods l33 may be otherwiseadjusted. In-lorfderto avoid bending of the impellerblades' due to gyroscopc forces, the rods 28 fa'nd 29, equalizer bar 23'0, springs 36 and-SLigTOVernors I6, I1,\II611and II-v1 are proportionedntfonly to givesuitable operat` ing characteristics to "the 'limpellen =but 'also "to provide weight for i balancing 'the impeller s'tricture. In order to achievelthislastibalance it-1in'a5 be |desirable to dispose Cthero'ds28 and'29"'a'nd their corresponding spoiIer'sfor--governors on .oppo-site sides of the'iinpellrbladeas shwnffor instance, in Fig.'3. Y

Another important 'feature residirig in?4 the s'e of the weighted members i-el'andrez'is' thatjthey not only provide a balancing arrangemeitwhich prevents large vibrational stresses, `but at the same time provide additional A"morneiituiiitothe blade structure afte'rit hasstartd'itsrotation without materially increasing the" drag, 'thereby smoothing out speed changes Adue'to r`,sudden changes in wind velocity without 'materiallj7' increasing the Wind Velocityi'ieeded'toistai't the lin.

pellerst rotating initially. Y Normally, 'without 'any' balancing-arrangement 8.. t0 :prevent the 'vibrational iand vvarious 'other stresses imparted to thefblades I-Uand I I. there isa vibrator'y effectlimparted to the blades, due tothepressure ofthe wind'thereagainst as well asbuffets imp'arted'byfgusts of wind which donot impart equal-forces to'theimpeller blades inf all or their positions.

nMoreover,y a rotating two-bladed impel1er,-due trelativechanges in `thedirection of centrifugal anw-gravitational:forces acting thereomhas varyirigfamountsofresultant forces acting on the various components thereof during one revolution with Ithe result that in eiect unbalanced forces are produced. The .streamlined weights '3l and 32-fnot only provide means -for balancing the two blade impeller about an axis corresponding to the axis of rotation of the impeller, but 'also may provide a balance for the rotational tendency' about an 2 axis corresponding `to the axis 'ofY supporting rod 33. Other advantages of this structure are thatfa i four "bladed effect isV obtained Without the extra nexpense Anecessaryfin providing an extra pair of cross' blades.

Preferably, the weighted members 3| and 32 and supporting rod :33 are so positioned 'and have such-mass' that the moment of inertia about an axis 'passing through the axis of -rod33iis substantially 'equal to the moment of inertia about a'naxis passing-throughethe longitudinalaxls of the impeller blade, andls-substantially equal to the moment of inertia about any axis in the plane ofthe drawing in Fig, 1 intermediate the axis of rod 33 :and'axisfof impeller'i. In that case the composite impeller structure under dynamic ,conditions behaves as a wheel or disc rotating about its center"of=gravity and does not shudder when thecomposite-impeller structure turns Withthe wind in-a direction perpendicular to the axis-of shaft I4. Itis understood that the composite impeller structures shown in Figs. 1 to 12 in conventional'manner' have a t'ailvane attached thereto arid are "pivotally mounted for rotation on a tower vwhereby the -axis of impeller rotation is always in the direction of the wind.

The balancing means Vheretoforedescribed in conjunction with an impeller having governing means'rotatably mounted with the impeller may be'usedequally well in an Varrangement wherein the speedof 'an impeller is controlled by side governing as shown in Figs. 13 and 14.

Figs. 13 Aand 1-4 show'the position -of an impeller inia'normal low velocity windand its-positionina relatively high velocity wind,-respec tively. The-impeller 50 is directly connected to shaft` 5I cfa power convertingunit such-as generator1'52 which is pivotally mounted onv spindle FIS-onza tower54. ATail vane -55 is pivotally .conricted 11o-generator housing extension 52B and ten'sionispring V56 connected therebetweenbiases th'e impeller structure to -afpostion wherein the rotating 'axis of impeller 50 and tail vane 55are parallelto one anotherwhen winds of low velocity impi'nge on the impeller structure. `Flexible ineaisiorlchain 51 for.v limiting movement of the iipellr structure due to the'action of tension spring 56-i`s connected between tail'vanev 551a'n`d thehousing ofgenerator'SZ *and is taut 'when the relativepositions ofthe tail vanef'andi'rnpeller structureareas's'ho'wninFigQlS.

-When winds Yalcove ya y'predetermined 'velocity impin-ge 'upon impeller'fS the-composite impeller 'stiiictu're ltrris' o'n- 'spindle v53 and'assunies p`o"si tion 'such-'ias shown in Fig-114 whereinla reduced component' of wind velocity 'eects rotation of iinpellrSIl. Ine other wordsf th'e '-s'ped-ffrdtation oi impeller is controlled automatically by displacingthe axis of shaft 5| in a degree depending upon wind velocity.

Therefore, the axis of the impeller structure changes in direction in accordance with wind intensity; and, in winds of varying intensity. large unbalanced forces act on the impeller structure when the impeller structure is unbalanced. These unbalanced forces. in the case of a twobladed impeller, no longer prevail when the impeller structure includes balancing means comprising rod |33 and weighted members |3| and |32 which are preferably disposed with the axis of rod |33 extending perpendicular to the axis of impeller 50 and in the plane of impeller rotation.

The particular balancing means shown in Figs. 13, 14 and 15 may be attached to rotatable sha-ft 5| in the same manner as rod 33 is fastened to impeller hub 9 and rotatable shaft Il! in Fig. 7. That is, rod |33 may pass through a radial hole in the impeller hub and rotatable shaft 5| and be fastened therein whereby the balancing means is symmetrically located about an axis defining the center of gravity of the impeller structure.

While I have shown and described the particuler embodiments of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects. and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention,

I claim:

1. A wind motor comprising a two bladed impeller mounted on a shaft at right angles thereto and adapted to rotate with the Ishaft about the longitudinal axis of the shaft, said blades being mounted in line with each other on opposite sides of the shaft, bearing means for said shaft supporting it for rotation about its longitudinal axis, a governing member attached to each impeller blade on one face thereof, an operating mechanism for said member attached to each impeller blade on the face thereof opposite to said member, said operating mechanisms holding said governing members in inoperative position at speeds of rotation of the impeller below a predetermined speed and causing said governing members to move gradually into increasingly operative positions on increase in the speed above said predetermined speed, said governing members serving when in operative position to reduce the rate of increase of speed of the impeller upon increase in wind velocity, a Ypair of supporting arms mounted in line with each other on opposite sides of the impeller shaft and in a line at right angles to the line of the impeller blades and perpendicular to the axis of the impeller shaft, and a balance weight attached to the extremity of each of said arms, said weights being streamlined for the direction of rotation of said impeller with which they rotate, said Weights being adjustably mounted on the ends of said arms, said adjustment when operated serving t0 change the length o the moment arms of said weights about the axis of said shaft, the structure comprising said impeller blades and attached governing members and operating mechanisms and balance weight-s having their masses so distributed that the moment of inertia of said structure about the 1ongitudinal axis of said supporting arms is substantially equal to the moment of inertia of said structure about the longitudinal axis of said impeller passing through the axis of said impeller shaft and that the masses of said structure on the Windward and leeward sides of a plane passing through said longitudinal axes of the supporting arms and impeller blades are substantially equal.

2. A two bladed impeller, a speed governing airfoil spoiler mounted on each of the blades, an operating mechanism for each of said spoilers attached to each blade on the face thereof opposite to said spoiler and extending to a point near the axis of rotation of said impeller, said mechanism including at least one spring near said axis arranged to hold said mechanism and spoilers in inoperative position at speeds of rotation of the impeller below a predetermined speed, and said mechanism being arranged to overcome the force of said spring above said predetermined speed to move said spoilers gradually into increasingly operative positions on increase in speed above said predetermined speed. weighted members connected to the impeller and disposed along an axis substantially perpendicular to the impeller blade length and substantially in the plane of rotation of the impeller blades, each of said airfoil spoilers being located near the tips of the respective blade to provide maximum turbulence, said weighted members being located relatively close to the center of the impeller to provide minimum turbulence, said weighted members and airfoil spoilers having such a weight distribution that the composite impeller structure is substantially balanced in three dimensions and the moments of inertia about axes longitudinal and transverse of the impeller are substantially equal.

3. In combination, a wind driven impeller mounted for rotation about an axis. sai-d impeller having blades, an airfoil spoiler mounted on each of said blades for spoiling the airstream adjacent thereto in response to rotational speeds of said impeller above a predetermined speed. an operating mechanism for each of said spoilers attached to the respective blade on the face thereof opposite to said spoiler and extending to a point near the axis of rotation of said impeller. said mechanism including at least one spring near said axis arranged to hold said mechanism and spoilers in inoperative position at speeds of rotation of the impeller below said predetermined speed, and said mechanism being arranged to overcome the force of said spring above said predetermined speed to move said spoilers gradually into increasingly operative positions in response to increase in rotational speed of said impeller above said predetermined speed. whereby tendency of the rotational speed oi said impeller to increase above said predetermined speed is reduced, said spoilers being located near the tip of the blades to produce maximum turbulence. said impeller and spoilers and the associated mechanism having such a mass distribution that the moment of inertia thereof is substantially unequal about perpendicular axes lying in the plane of rotation lof the impeller, and masses connected with said impeller for rotation therewith and lying on an axis of smaller moment thereby to increase the mass thereof in such direction and in such amount that the moment of inertia of said impeller together with said spoilers and associated mechanism and said masses is substantially equal about said perpendicular axes lying in the plane of rotation of said impeller, said masses being located relatively close to the center of the impeller to avoid undesired spoilage of the air stream.

JOHN R. ALBERS.

(References on following page) REFERENCE-s lCITED Number l2 'Name Date "Plucker Oct.27,' 1936 McColly Aug.'9, 1938 fAllen Feb, 28, 1939 fAlbers'et a1 Mar, 17, 1942 "Davis 'Jan.'18,1944

- FOREIGN --PATENTS Country 'Date 'Great' Britain Sept. 19,'1912 France Oct. 17, 1924 VGermany Nov. 21, 1933 France July 2, 1928 Germany Mar. 2, 1939 

